Questions tagged [digital-communications]
Related to all communication systems that use a given digital sequence as an interface between the source and the channel input.
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How do we change the digital encoding method of a signal? (eg. From Unipolar NRZ to Polar NRZ)
We have different digital encoding methods like Unipolar, Polar, Bipolar, Manchester. I was working with stm32f411re and I saw USART uses Unipolar NRZ. So how do we change this encoding methods?
I ...
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With modern connectors, is the metal shell used as a conductor?
Does the metal shell of a connector, such as USB and HDMI, serve a conducting purpose? The metal shell of my TV's HDMI terminal is corroded. Should I make effort to have it contacting and conducting ...
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How can I connect the DVP camera output with Raspberry Pi or other MCU?
I have a MT9V034 image sensor module and I want to use its 8-bit DVP output. Does anyone know how to connect a DVP interface with a Raspberry Pi and show some graph?
I have read the Raspberry Pi user ...
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PIC MCC I2C setup help
I have made use of the MSSP1 in MPLABx's MCC (code configurator). I have set it up as an I2C slave device and initialized the setup in the code provided. I am making use of a MCP2221 as a master ...
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Is digital signal transmission different from square wave?
I am just getting into signal processing and am having trouble understanding where generating square-waves by means of harmonics is useful.
Digital signal transmission can be achieved by changing ...
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How many UART interfaces can be used in this MCU
I want to understand how many UART interfaces can I use in this ATSAMD21 MCU.
I searched for "UART" in the datasheet to find which pins and how many UART interfaces I can connect to. But I ...
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The best way to light an LED at a distance
I need to control an LED (SSR) at a someway-long distance of about 20 meters (60 feet) from a microcontroller.
A simple LED on/off control type where I could keep it on for a long period of time. The ...
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How to recreate this type of sine jamming?
I'm trying to recreate this type of sine/tonal jamming in Python as part of my graduation project.
I found this dataset in a published paper that described this type of jamming as "Sine Jamming&...
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FSK modulation and inverting mark and space bits
Quick theory to application question.
In Frequency shift keying we usually have the output of a sequence generator into a VCO, then this leads to a high frequency for the mark bit and a lower ...
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Read analog value with microcontroller without ADC
I have an AT89S51 microchip from Atmel. I want to read a value from a node in a circuit that can be either ~0V or ~5V (it's the output of a comparator, so the comparator itself is my ADC).
Is it ...
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Effects of discretisation on bandwidth of low-pass filter
Consider a first order low-pass filter, with a cut-off frequency of (2π)*(8000). This filter will have a cut-off frequency at (2π)(8000), as well as a pole there.
$$
H(s) = \frac{1}{(\tau.s + 1)}
$$
...
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When do we assume a wireless communications' channel reciprocity and non-reciprocity?
When I read wireless communications literature, I encountered both channel reciprocity and non-reciprocity assumptions for two-way communication scenarios involving A-to-B and B-to-A fading channels.
...
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Why does a simple BLDC motor circuit need CAN communication?
I was looking at this open source BLDC motor circuit, and I noticed it had a CAN bus transceiver apart of the circuit. I don't understand why this circuit would need a CAN bus transceiver? Does this ...
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Align symbol period in GFSK communications
To learn more about communication systems I have been using an SDR (RTL2832U) and a 918 MHz transceiver (RFD900+) which sends signals using 2 GFSK. The deviation of my RFD900+ from the center ...
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How can I find common factor in convolutional coding, to check if it's catastrophic or not?
I'm studing Digital Communications - Fundamentals and Applications by Bernard Sklar.
About channel coding - convolutional coding, looking for a common factor is a key to check if it's catastrophic or ...
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Why I2C ultra-fast mode support only write operation
Below image is from TI I2C training.
It says that Ultra-fast mode supports write only and omits some standard I2C feature.
This does not say why it is supporting only write and what are the features ...
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Interface ADC with STM32F103 over SPI
The ADC is ADS1256 which is a 24 bit 8 channel ADC. I will use 1 kHz sampling rate and there will be 3 ADCs, 21 channels used in total. The channels will be single ended. I plan to run the MCU on a 40 ...
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Understanding line coding on 10/100 mbps ethernet
While learning about the way bits are sent over ethernet (twisted pair), I came across this table:
What I don't understand is:
Do all of them except 100Base-TX use only 1 pair for both RX and TX?
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"phase gradient", what is it?
I have found an interesting paper published on the website of Huawei "Very-Low-Earth-Orbit Satellite Networks for 6G"
I have a question regarding the following part:
"3D UE- centric ...
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Linear Equalizer LMS algorithm
I have to realise a Linear Spaced Equalizer using LMS algorithm on Matlab by writing the code from this
The algorithm to be implemented is iterative. It starts with an initial value (initialisation) ...
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I have three absolute rotary encoders that can output analog sinusoidal voltages OR SSI signals. I need to send their signal to a single pin. How?
The rotary encoders I'm using are sold with several different output options. Analogue sinusoidal (90* phase shifted sin and cosine signal), Incremental output (90* phase shifted quadrature signals ...
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Samsung's demonstration of THz communication
I have recently found articles about Samsung's demonstration of THz communication.
Samsung demonstrates 6G THz wireless communication
Samsung demos 6G using Terahertz spectrum
They announced they ...
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Amplitude Phase Shift Keying: Voltage Level Determination at Receiver
I am learning about communications via some of the coursework available here. In lecture 6 of the coursework, the author introduces the concept of Amplitude Shift Keying, and I have a question which ...
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How is 100BASE-T1 Full duplex? [duplicate]
100BASE-T1 consists of a single differential pair of wires, using tri-state logic.
Everything I have found so far says that 100BASE-T1 is full duplex but nothing has explained how this actually works ...
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Intersymbol interference on PAM Trasmitter
I would like to simulate on Matlab a PAM signal which, travelling on a time-dispersive communication channel, contains intersymbol interference (ISI).
I have 'built' the transmitter by generating:
8-...
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Selectable digital communcation links between any two of eight devices [closed]
I'm building a small computer where I have 8 units that need to communicate with each other.
Each unit also has eight serial 6 Mbps async lines, so 16 pins.
The driver I'm looking for should be able ...
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How to read the device ID of an AARDVARK adapter? [closed]
I am using a Total Phase AARDVARK adapter as an I2C host. Each AARDVARK has a unique ID (or S/N) that's used for communication with the software. That ID is printed on a sticker on the device. Is ...
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Key considerations for designing Ethernet-based devices [closed]
I am working on a camera board that can send video over Ethernet. I've never designed hardware for any communication protocols other than I2C and SPI and am aware that Ethernet is much more ...
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How to compute a data rate "loss"?
I am studying 6G communication. There are a lot of publication about it, frequency, latency, BW and other KPIs.[1],[2]
Now one of the most popular research topics is an integration non-terrestrial ...
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Interfacing two Attinys MCUS by one pwm wire only. Is it a possible approach?
I have one Attiny85 and an Attiny167 that are connected by a 4 pin one meter cable. The Attiny85 controls a sensor at one end of the cable, and the Attiny167 controls the battery and other stuff at ...
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Receiver Automatic Gain Control purpose
Receiver AGC objective is to have a constant amplitude signal in order to optimize the receiver performance, so it should respond according to the amplitude of the signal of interest and not to the ...
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FTDI's FT_GetStatus always returns 0 bytes in the transmit queue of FT4232
Kind of a question in-between StackOverflow and Electrical, but I'm taking my chances here.
I'm streaming data continuously to a FT4232 and I tracked down a systematic issue I had occuring always at ...
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Is it sufficient to put 5.1k pulldowns on CC1 and CC2 of USBC to get 5V 1.5A?
My device needs 1.5A at 5V from a USBC connector. I already have 5.1k resistors in place on both CC1 and CC2 and a fuse rated for 1.5A. However, I have read on here in another thread that apparently ...
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Do we HAVE to draw no more than 2.5 mA in USB suspend mode for a device to be enumerated?
I am currently trying to make an FT231XS recognised by a Windows 10 computer, and it always says the device is unrecognised as soon as I plug it in (c.f. this other thread).
That board is always ...
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Isolators and Level shifters - default to logic 1
I've been making my first boards to do some testing in power electronics. I'm testing unpowered circuits, and there's something that baffles me.
I'm testing if pulses appear correctly on gate drives ...
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TXS0108 bidirectional communication with ESP32
Due to the ESP32 3.3V logic, I need a level shifter in order to communicate with two 5V logic SDI-12 sensors (two sensors on two different buses.)
I chose the TXS0108 from Sparkfun for this purpose, ...
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Relation between AWGN and bit rate
I want to get the value of the maximum rate of digital information to be transmitted by carrier modulation through an AWGN channel with a bandwidth of \$ 100\ \mathrm{kHz} \$ and \$ N_o = 10^{-10}\ \...
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Why use 128b/132b line coding?
Some background/research: for various reasons, many protocols use 8b/10b encoding, which encodes 8 bits of data in 10 bits of line code. However, doing so adds 25% overhead to the number of bits ...
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Time period for analysing an instantaneous sound wave and then converting it to the frequency domain?
I am confused about how a signal is analysed in the frequency domain after being recorded in the time domain instantly.
Does the spectrum of frequencies that are displayed based on a previous period, ...
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Why does norm of the PAM bandpass signal give energy of the pulse over two?
I would like to understand why \$\int_{-\infty}^{+\infty}g^2(t)cos^2(2\pi f_c t)dt = \mathcal{E}_g/2\$
\$g(t)\$ is a pulse of duration T.
the background is:
reading the book "Digital ...
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I and Q from a time series
Say I have a QPSK signal transmitted at a carrier frequency of 5 MHz. The message rate is 100 kHz. If I use a Tektronix scope or data acquisition box to digitize and capture the signal (not a direct ...
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Why are analog signals preferred for high-frequency applications? [closed]
I really don't see what benefit analog signals would give over digital ones in this case.
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I2C scan returns more devices than connected
I am using an ESP32 WROOM 32D on a self-designed PCB to read from two sensors:
an IMU (LSM6DSO32) and a pressure sensor (LPS22df).
The IMU reads and writes flawlessly, while the pressure sensor hasn't ...
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UART - Reduce 4 V to 3 V
I have a 4 V microcontroller communicating with a SoC over UART (most likely 9600 baud), whereby the maximum input voltage on the SoC's RX input is 3.1 V. Because of this, I'd like to step the logic ...
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Differential manchester encoding and data rate
I am trying to understand the specifications given by Transceiver chip (FT5000).
This chip encodes databits into 'differential manchester encoding'(DME) technique and send it over twisted pair.
The ...
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How is Alignment Marker Used for Deskew in Ethernet Protocol?
I've been reading through the 802.3 standards recently and am learning about alignment markers inserted as blocks in ethernet frames to deskew PCS channels.
While I can find information about the bit-...
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How does multiplying the modulated signal "AGAIN" by the carrier frequency transfer the spectrum back to its original position?
I have some trouble understanding the demodulation of a signal. SI understand how we multiply the message signal by the carrier signal then chuck it through a channel, but on the receiver side I don't ...
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Photodiode speed limitation
I have a system which demands optical data transmission since rotating parts are present. A mixed mechanical-electrical engineering project has led us to use photodiodes to receive data from one ...
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Why does an optical channel require non-negative and real signal to transmit?
I'm trying to find an answer to two questions. In most of the papers they use the term without further explaining the reasons.
Why does intensity modulation require real and non-negative signals to ...
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What is order of signals in streaming interface handshake?
A simple streaming interface consists of two signals, ready and valid. The streaming source asserts its valid output and the streaming sink asserts its ready output.
Data is transmitted when ready and ...
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